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Sep 21, 2013
09/13

by
Somendra M. Bhattacharjee; Thomas Nattermann; Christopher Ronnewinkel

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Phases and phase transitions in pure and doped spin-Peierls system CuGeO_3 are considered on the basis of a Landau-theory. In particular we discuss the critical behaviour, the soliton width and the low temperature specific heat of the incommensurate phase. We show, that dilution leads always to the destruction of long range order in this phase, which is replaced by an algebraic decay of correlations if the disorder is weak.

Source: http://arxiv.org/abs/cond-mat/9711094v1

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Sep 21, 2013
09/13

by
W. -D. Nowak; O. Teryaev; A. Tkabladze

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We discuss the double spin asymmetries in charmonium hadroproduction with nonzero transverse momenta at fixed target energies, $\sqrt{s}\simeq40$ GeV, within the framework of the factorization approach. It is shown that the color octet contribution is dominant in the asymmetries. The size of the asymmetries and the projected statistical errors in a future option of HERA with longitudinally polarized protons scattering off a polarized target (HERA-$\vec N$) should allow to distinguish between...

Source: http://arxiv.org/abs/hep-ph/9711290v1

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Sep 21, 2013
09/13

by
Misha Verbitsky

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Let X be a hyperkaehler manifold. Trianalytic subvarieties of X are subvarieties which are complex analytic with respect to all complex structures induced by the hyperkaehler structure. Given a K3 surface M, the Hilbert scheme classifying zero-dimensional subschemes of M admits a hyperkaehler structure. We show that for M generic, there are no trianalytic subvarieties of the Hilbert scheme. This implies that a generic deformation of the Hilbert scheme of K3 has no complex subvarieties.

Source: http://arxiv.org/abs/alg-geom/9705004v2

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Sep 21, 2013
09/13

by
G. Dahmen; S. Huettemeister; T. L. Wilson; R. Mauersberger

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The large scale structure and physics of molecular gas in the Galactic center region is discussed based on the analysis of a 9' resolution survey of the Galactic center region in the J=1->0 line of C^18O. Emphasis is placed on the comparison with ^12CO(1--0) data. The line shapes of C^18O(1--0) and ^12CO(1--0) differ significantly. The ratio of the intensities of the two isotopomers in the Galactic center region is generally higher than the value of ~15 expected from the ``Standard...

Source: http://arxiv.org/abs/astro-ph/9711117v1

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Sep 21, 2013
09/13

by
Robert H. Brandenberger

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The hypothesis that the Universe underwent a period of exponential expansion at very early times has become the most popular theory of the early Universe. Not only does it solve some of the problems of standard big bang cosmology, but it also provides a causal theory for the origin of primordial density fluctuations which may explain the observed density inhomogeneities and cosmic microwave fluctuations in the Universe. In these lectures, a review of the basic principles of inflationary...

Source: http://arxiv.org/abs/astro-ph/9711106v1

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Sep 21, 2013
09/13

by
K. Ziegler

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The mechanism of delocalization of two-dimensional Dirac fermions with random mass is investigated, using a superfield representation. Although localization effects are very strong, one fermion component can delocalize due to the spontaneous breaking of a special supersymmetry of the model. The delocalized fermion has a non-singular density of states and is decribed by a diffusion propagator. Supersymmetry is restored if the mean of the random mass is sufficiently large. This is accompanied by...

Source: http://arxiv.org/abs/cond-mat/9711097v1

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Sep 21, 2013
09/13

by
Natan Andrei; Gergely T. Zimanyi; Gerd Schoen

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We study two quantum dots in the limit of strong dot-lead coupling and weak dot-dot tunneling. The model maps on Ising-coupled Kondo impurities. We argue that a new quantum critical fixed point exists at an intermediate value of the mutual capacitance, supporting non-Fermi liquid behaviour. We construct the total conductance across the double dot structure. It exhibits a strongly peaked behaviour as a function of the mutual capacitance, gate voltage, and temperature.

Source: http://arxiv.org/abs/cond-mat/9711098v1

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Sep 21, 2013
09/13

by
Adam Parusinski

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We show that every $\mu$-constant family of isolated hypersurface singularities of type f(x) + tg(x), where t is a parameter, is topologically trivial. In the proof we construct explicitely a vector field trivializing the family. The proof uses only the curve selection lemma and hence, for an appropriately translated statement, also works over the reals. Some applications to the study of singularities at infinity of complex polynomials are given.

Source: http://arxiv.org/abs/alg-geom/9711014v1

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Sep 21, 2013
09/13

by
A. O. Barvinsky; C. Kiefer

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We present a systematic expansion of all constraint equations in canonical quantum gravity up to the order of the inverse Planck mass squared. It is demonstrated that this method generates the conventional Feynman diagrammatic technique involving graviton loops and vertices. It also reveals explicitly the back reaction effects of quantized matter and graviton vacuum polarization. This provides an explicit correspondence between the frameworks of canonical and covariant quantum gravity in the...

Source: http://arxiv.org/abs/gr-qc/9711037v1

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Sep 21, 2013
09/13

by
A. Pineda; F. J. Yndurain

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We include two loop, relativistic one loop and second order relativistic tree level corrections, plus leading nonperturbative contributions, to obtain a calculation of the lower states in the heavy quarkonium spectrum correct up to, and including, $O(\alpha_s^4)$ and leading $\Lambda^4/m^4$ terms. This allows us, in particular, to obtain a model independent determination of the pole masses of the $b, c$ quarks, $$m_b=5 015^{+110}_{-70} mev; m_c=1 884^{+222}_{-133} mev$$ to which correspond the...

Source: http://arxiv.org/abs/hep-ph/9711287v1

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Sep 21, 2013
09/13

by
Fabio Riccioni; Augusto Sagnotti

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We review some results on the complete coupling between tensor and vector multiplets in six-dimensional $(1,0)$ supergravity.

Source: http://arxiv.org/abs/hep-th/9711077v1

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Sep 21, 2013
09/13

by
W. Collmar; V. Schoenfelder; H. Bloemen; J. J. Blom; W. Hermsen; M. McConnell; J. G. Stacy; K. Bennett; O. R. Williams

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The EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed at energies above 100 MeV strong gamma-ray flares with short-term time variability from the gamma-ray blazars 3C 279 and PKS 1622-297. During these flaring periods both blazars have been detected by the COMPTEL experiment aboard CGRO at photon energies of about 10 MeV, revealing simultaneous gamma-ray activity down to these energies. For both cases the derived fluxes exceed those measured in previous observations,...

Source: http://arxiv.org/abs/astro-ph/9711111v1

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Sep 21, 2013
09/13

by
Edmund Grimley-Evans

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Although adequate models of human language for syntactic analysis and semantic interpretation are of at least context-free complexity, for applications such as speech processing in which speed is important finite-state models are often preferred. These requirements may be reconciled by using the more complex grammar to automatically derive a finite-state approximation which can then be used as a filter to guide speech recognition or to reject many hypotheses at an early stage of processing. A...

Source: http://arxiv.org/abs/cmp-lg/9711002v1

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Sep 19, 2013
09/13

by
Naoya Takahashi; Tsutomu Kambe; Tohru Nakano; Toshiyuki Gotoh; Kiyoshi Yamamoto

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Two conditional averages for the increment Delta(x,x+r) = T(x)-T(x+r) of the scalar field are estimated for DNS data: H(Delta)= and G(Delta)= . The probability density function P(Delta) for Delta(x,x+r) is also calculated. If Delta, P(Delta), H(Delta), and G(Delta) are expressed as theta, P(theta), h(theta), and g(theta) in a dimensionless form, the data analysis has revealed interesting simple relationships between them. These relations may be helpful to construct a turbulence model.

Source: http://arxiv.org/abs/chao-dyn/9709019v4

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Sep 21, 2013
09/13

by
Chandan Dasgupta; Oriol T. Valls

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Transitions between ``glassy'' local minima of a model free-energy functional for a dense hard-sphere system are studied numerically using a ``microcanonical'' Monte Carlo method that enables us to obtain the transition probability as a function of the free energy and the Monte Carlo ``time''. The growth of the height of the effective free energy barrier with density is found to be consistent with a Vogel-Fulcher law. The dependence of the transition probability on time indicates that this...

Source: http://arxiv.org/abs/cond-mat/9711095v1

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Sep 21, 2013
09/13

by
Lothar Goettsche

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I give a conjectural generating function for the numbers of $\delta$-nodal curves in a linear system of dimension $\delta$ on an algebraic surface. It reproduces the results of Vainsencher for the case $\delta\le 6$ and Kleiman-Piene for the case $\delta\le 8$. The numbers of curves are expressed in terms of five universal power series, three of which I give explicitly as quasimodular forms. This gives in particular the numbers of curves of arbitrary genus on a K3 surface and an abelian surface...

Source: http://arxiv.org/abs/alg-geom/9711012v1

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Sep 21, 2013
09/13

by
E. Oset; A. Ramos

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The s-wave meson-nucleon interaction in the $S = -1$ sector is studied by means of coupled-channel Lippmann Schwinger equations, using the lowest order chiral Lagrangian and a cut off to regularize the loop integrals. The method reproduces succesfully the $\Lambda (1405)$ resonance and the $K^- p \to K^- p, \bar{K}^0 n, \pi^0 \Lambda, \pi^0 \Sigma, \pi^+ \Sigma^-, \pi^- \Sigma^+$ cross sections at low energies. The inclusion of the $\eta \Lambda, \eta \Sigma^0$ channels in the coupled system is...

Source: http://arxiv.org/abs/nucl-th/9711022v1

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Sep 21, 2013
09/13

by
Atuko Nisikawa; Asao Habe; Nobuo Isibasi

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We have studied the effects of Compton cooling on cooling flow by performing numerical hydrodynamic calculations of the time evolution of hot gas in clusters of galaxies with luminous quasars. We assumed various temperatures for the hot intracluster gas. We have shown that the Compton cooling due to very luminous quasar is effective in inducing cooling flow, before radiative cooling flow is realized. The mass flux due to the cooling flow increases with time, as the Compton cooled region...

Source: http://arxiv.org/abs/astro-ph/9711118v1

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Sep 21, 2013
09/13

by
Stacy McGaugh; Erwin de Blok

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A number of observations strongly suggest that the baryon fraction is not a universal constant. One obvious interpretation is that there is some distribution of Fb, and the different observations sample different portions of the distribution. However, the small intrinsic scatter in the Tully-Fisher relation requires that the baryon fraction be very nearly universal. It is not easy to resolve this paradox in the framework of the standard picture.

Source: http://arxiv.org/abs/astro-ph/9711119v1

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Sep 21, 2013
09/13

by
S. F. King; Q. Shafi

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We present a minimal string-inspired supersymmetric $SU(4) \times SU(2)_L \times SU(2)_R$ model, and provide a detailed analysis of the symmetry breaking potential in this model, based on a generalisation of that recently proposed by Dvali, Lazarides and Shafi. The model contains a global U(1) R-symmetry and reduces to the MSSM at low energies. However it improves on the MSSM since it explains the magnitude of its $\mu$ term and gives a prediction for $\tan \beta \simeq m_t/m_b$. It also...

Source: http://arxiv.org/abs/hep-ph/9711288v1

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Sep 21, 2013
09/13

by
D. Marsden; R. E. Rothschild; C. Kouveliotou; S. Dieters; J. van Paradijs

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We discuss observations of the soft gamma repeater SGR 1806-20 during the RXTE Target of Opportunity observations made in November 1996. During the ~50 ksec RXTE observation, HEXTE (15-250 keV) detected 17 bursts from the source, with fluxes ranging from 3 x 10^{-9} to 2.2 x 10^{-7} ergs cm^{-2} s^{-1} (20-100 keV). We obtained spectra for the brighter HEXTE by fitting thermal bremsstrahlung and power law functions over the energy range 17 - 200 keV. The best-fit temperatures and photon indices...

Source: http://arxiv.org/abs/astro-ph/9711120v1

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Sep 21, 2013
09/13

by
D. Schildknecht

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It is shown that the HERA experimental data on deep inelastic scattering at low values of the scaling variable x < 0.05 are in good agreement with predictions from Generalized Vector Dominance in the full kinematic range from Q2 = 0 (photoproduction) to Q2 = 350 GeV.

Source: http://arxiv.org/abs/hep-ph/9711291v1

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Sep 21, 2013
09/13

by
Bang-Gui Liu; Gerd Czycholl

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An infinite-$U$ term is introduced into the Holstein-Primakoff-transformed magnon hamiltonian of quantum Heisenberg magnetic models of spin $s$. This term removes the unphysical spin wave states on every site and truncates automatically the expansion in powers of the magnon occupation operator. The resultant strong-coupling magnon hamiltonians are accurately equivalent to the original spin hamiltonians. The on-site $U$ levels and their implications are studied. Within a simple decoupling...

Source: http://arxiv.org/abs/cond-mat/9711086v1

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Sep 21, 2013
09/13

by
Sungsoo S. Kim; Hyung Mok Lee

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We examine the corecollapse times of isolated, two-mass-component star clusters using Fokker-Planck models. With initial condition of Plummer models, we find that the corecollapse times of clusters with M_1/M_2 >> 1 are well correlated with (N_1/N_2)^{1/2}(m_1/m_2)^{2} t_{rh}, where M_1/M_2 and m_1/m_2 are the light to heavy component total and individual mass ratios, respectively, N_1/N_2 is the number ratio, and t_{rh} is the initial half-mass relaxation time scale. We also find...

Source: http://arxiv.org/abs/astro-ph/9711109v1

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Sep 21, 2013
09/13

by
D. Lin; E. P. Liang

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In a hybrid thermal-nonthermal plasma, we find that the dominant emission and absorption mechanisms are synchrotron by nonthermal electrons and bremsstrahlung by thermal electrons. These two processes significantly change the spectrum from inverse Compton scatterings at low energies. We also find that Coulomb collisions are effective in cooling down the lower energy electrons but do not significantly alter the emission pattern. Compton cooling is more effective in changing emission and...

Source: http://arxiv.org/abs/astro-ph/9711107v1

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Sep 21, 2013
09/13

by
Vladimir Hizhnyakov

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A nonperturbative theory of multiphonon anharmonic decay of strongly excited local mode is developed whereby the mode is considered classically and phonons, quantum mechanically. The decay rate of the mode is expressed via the negative frequency parts of the phonon pair correlation functions. In the case of two-phonon decay the later satisfy the linear integral equations while in the case of two- and more-phonon decay they satisfy the nonlinear integral equations. As a result, the processes...

Source: http://arxiv.org/abs/cond-mat/9711090v1

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Sep 21, 2013
09/13

by
Roberto Trasarti-Battistoni

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We present a large catalog of $N_G \approx 200$ loose groups of galaxies selected from the Perseus-Pisces redshift Survey.

Source: http://arxiv.org/abs/astro-ph/9711114v1

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Sep 21, 2013
09/13

by
Sungsoo S. Kim; Hyung Mok Lee; Jeremy Goodman

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Two-component (normal and degenerate stars) models are the simplest realization of clusters with a mass spectrum because high mass stars evolve quickly into degenerates, while low mass stars remain on the main-sequence for the age of the universe. Here we examine the evolution of isolated globular clusters using two-component Fokker-Planck (FP) models that include heating by binaries formed in tidal capture and in three-body encounters. Three-body binary heating dominates and the postcollapse...

Source: http://arxiv.org/abs/astro-ph/9711108v1

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Sep 21, 2013
09/13

by
N. V. Krasnikov; G. Kreyerhoff; R. Rodenberg

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We study the dependence of the Higgs boson mass on the supersymmetry breaking scale in the minimal supersymmetric extension of the standard Weinberg-Salam model. In particular, we find that for supersymmetry breaking scale $10^8$ GeV $\leq M_s \leq 10^{16}$ GeV and for $m^{pole}_{top} = 175 \pm 5 $ GeV the Higgs boson mass is 120 GeV $ \leq m_h \leq 160 $ GeV

Source: http://arxiv.org/abs/hep-ph/9711286v1

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Sep 21, 2013
09/13

by
M. Beth Ruskai; Elisabeth Werner

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The Error Function \begin{eqnarray} V(x) & \equiv & \sqrt{\pi} e^{x^2} [1 - \hbox{erf}(x)] \\ & = & \int_0^\infty \frac{ e^{-u} }{\sqrt{x^2 + u}} du = 2 e^{x^2}\int_x^\infty e^{-t^2} dt \nonumber \end{eqnarray} arises in many contexts, from probability to mathematical physics. We give estimates for the Error Function from above and below which are optimal within a certain class of functions.

Source: http://arxiv.org/abs/math/9711207v1

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Sep 21, 2013
09/13

by
Stefan Riezler

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This paper addresses two central problems for probabilistic processing models: parameter estimation from incomplete data and efficient retrieval of most probable analyses. These questions have been answered satisfactorily only for probabilistic regular and context-free models. We address these problems for a more expressive probabilistic constraint logic programming model. We present a log-linear probability model for probabilistic constraint logic programming. On top of this model we define an...

Source: http://arxiv.org/abs/cmp-lg/9711001v1

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Sep 21, 2013
09/13

by
J. Fujimoto; K. Hikasa; T. Ishikawa; M. Jimbo; T. Kaneko; K. Kato; S. Kawabata; T. Kon; M. Kuroda; Y. Kurihara; T. Munehisa; D. Perret-Gallix; Y. Shimizu; H. Tanaka

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\susy23 is a Monte-Carlo package for generating supersymmetric (SUSY) processes at $e^+e^-$ colliders. Twenty-three types of SUSY processes with 2 or 3 final state particles at tree level are included in version 2.0. {\susy23} addresses event simulation requirements at $e^+e^-$ colliders such as LEP. Matrix elements are generated by GRACE with the helicity amplitude method for processes involving massive fermions. The phase space integration of the matrix element gives the total and...

Source: http://arxiv.org/abs/hep-ph/9711283v1

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Sep 21, 2013
09/13

by
Matthew D. Lehnert; Robert H. Becker

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We present spectra taken with the Low Resolution Imaging Spectrograph on the Keck 10m telescope of spatially-resolved structures ("fuzz") around the high-redshift radio-loud quasars PKS 0445+097 (z=2.108) and PKS 2338+042 (z=2.589). For PKS 0445+097 we find that there is faint extended HeII1640 and CIII]1909 from the quasar host galaxy. Both of the lines are broad (FWHM(HeII)=1000+-200 km/s and FWHM=2200+-600 km/s). The limits on the fluxes, the large line widths, and the line ratio...

Source: http://arxiv.org/abs/astro-ph/9711113v1

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Sep 21, 2013
09/13

by
M. Rampp; E. Mueller; M. Ruffert

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We report on the first three-dimensional hydrodynamic simulations of secular and dynamical non-axisymmetric instabilities in collapsing, rapidly rotating stellar cores which extend well beyond core bounce. The resulting gravitational radiation has been calculated using the quadrupole approximation. We find that secular instabilities do not occur during the simulated time interval of several 10 ms. Models which become dynamically unstable during core collapse show a strong nonlinear growth of...

Source: http://arxiv.org/abs/astro-ph/9711122v1

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Sep 21, 2013
09/13

by
Henry A. Kobulnicky

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The nitrogen and oxygen abundances in the warm ionized gas of low-mass, metal-poor galaxies appear surprisingly homogeneous considering the prevalence of large HII regions, which contain hundreds of massive stars. Of the six galaxies with extensive optical spectroscopy, only the largest and most metal-rich, the LMC, shows evidence for a chemical gradient akin to those commonly seen in spirals. Furthermore, no significant localized chemical fluctuations are found in the vicinity of young star...

Source: http://arxiv.org/abs/astro-ph/9711077v1

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Sep 21, 2013
09/13

by
P. H. M. van Loosdrecht

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An overview is given of Raman and infrared spectroscopic studies of the inorganic spin-Peierls compound CuGeO$_3$, with an emphasis on the magnetic fluctuations in the uniform, dimerized, and high field phases of this quasi one dimensional magneto-elastic compound.

Source: http://arxiv.org/abs/cond-mat/9711091v1

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Sep 21, 2013
09/13

by
Michael Farber; Gabriel Katz; Jerome Levine

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We consider the problem of whether it is possible to improve the Novikov inequalities for closed 1-forms, or any other inequalities of a similar nature, if we assume, additionally, that the given 1-form is harmonic with respect to some Riemannian metric. We show that, under suitable assumptions, it is impossible. We use, in an essential way, a theorem of E.Calabi characterizing 1-forms which are harmonic with respect to some metric. We also study some interesting examples illustrating our...

Source: http://arxiv.org/abs/dg-ga/9711007v1

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Sep 21, 2013
09/13

by
Lars Brink; Alexander Turbiner; Niclas Wyllard

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We propose to parametrize the configuration space of one-dimensional quantum systems of N identical particles by the elementary symmetric polynomials of bosonic and fermionic coordinates. It is shown that in this parametrization the Hamiltonians of the A_N, BC_N, B_N, C_N and D_N Calogero and Sutherland models, as well as their supersymmetric generalizations, can be expressed -- for arbitrary values of the coupling constants -- as quadratic polynomials in the generators of a Borel subalgebra of...

Source: http://arxiv.org/abs/hep-th/9705219v2

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Sep 21, 2013
09/13

by
Karol Zyczkowski; Wojciech Slomczynski

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We define a metric in the space of quantum states taking the Monge distance between corresponding Husimi distributions (Q--functions). This quantity fulfills the axioms of a metric and satisfies the following semiclassical property: the distance between two coherent states is equal to the Euclidean distance between corresponding points in the classical phase space. We compute analytically distances between certain states (coherent, squeezed, Fock and thermal) and discuss a scheme for numerical...

Source: http://arxiv.org/abs/quant-ph/9711011v1

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Sep 21, 2013
09/13

by
U. Kraemmer; A. Rebhan

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In two recent preprints (hep-th/9710131 and hep-th/9710132), Abe and Nakanishi have claimed that the proof of the gauge independence of the conformal anomaly of the bosonic string as given by us in 1988 was wrong. A similar allegation has been made concerning our proof of the gauge independence of the sum of the ghost number and Lagrange multiplier anomalies in non-conformal gauges. In this short note we refute their criticism by explaining the simple logic of our proofs and emphasizing the...

Source: http://arxiv.org/abs/hep-th/9711075v1

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Sep 21, 2013
09/13

by
Mans Henningson

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I review my work together with Piljin Yi on the spectrum of BPS-saturated states in N = 2 supersymmetric Yang-Mills theories. In an M-theory description, such states are realized as certain two-brane configurations. We first show how the central charge of the N = 2 algebra arises from the two-form central charge of the eleven-dimensional supersymmetry algebra, and derive the condition for a two-brane configuration to be BPS-saturated. We then discuss how the topology of the two-brane determines...

Source: http://arxiv.org/abs/hep-th/9711076v1

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Sep 21, 2013
09/13

by
E. Fradkin; Chetan Nayak; A. Tsvelik; Frank Wilczek

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We present a low-energy effective field theory describing the universality class of the Pfaffian quantum Hall state. To arrive at this theory, we observe that the edge theory of the Pfaffian state of bosons at $\nu=1$ is an $SU(2)_2$ Kac-Moody algebra. It follows that the corresponding bulk effective field theory is an SU(2) Chern-Simons theory with coupling constant $k=2$. The effective field theories for other Pfaffian states, such as the fermionic one at $\nu=1/2$ are obtained by a...

Source: http://arxiv.org/abs/cond-mat/9711087v1

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Sep 21, 2013
09/13

by
Nicola Masetti; Massimo Della Valle

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We have performed a Discrete Fourier Transform on 136 CCD B, V and R frames of the Z Cam-type dwarf nova V1101 Aql. Our analysis indicates as possible orbital period P_orb =3.46 hours, though we cannot exclude the alias at 4.00 hours. We estimate the distance to the system to be about 300 pc. We possibly discovered a bright bow-shaped nebulosity around the object.

Source: http://arxiv.org/abs/astro-ph/9711115v1

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Sep 21, 2013
09/13

by
H. Aubin; K. Behnia; S. Ooi; T. Tamegai

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We studied the thermal conductivity of a Bi_2Sr_2CaCu_2O_8 single crystal as a function of a magnetic field ramped up and down and then reversed. As recently discovered by Krishana et al., we observed a field-independent thermal conductivity above a threshold field. However, our measurements show that the magnitude of background thermal conductivity depends on the field profile in the sample. This is incompatible with the interpretation put forward by Krishana and co-workers.

Source: http://arxiv.org/abs/cond-mat/9711093v1

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Sep 21, 2013
09/13

by
Roman Lietava; Jan Pisut

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Data on mean numbers of $\Lambda$, $\bar\Lambda$, K's and on the total number $ $ of pairs of strange valence quarks in final state hadrons in hadronic and nuclear collisions at CERN- SPS energies are studied as a function of the mean number $$ of nucleon- nucleon collisions. Results give indications of an almost linear dependence over most of the region of $$. This in turn points out to strangeness being produced mostly in the central rapidity region of nucleon- nucleon collisions by a...

Source: http://arxiv.org/abs/hep-ph/9711285v1

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Sep 21, 2013
09/13

by
Vicente Muñoz

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We compute some Gromov-Witten invariants of the moduli space of odd degree rank two stable vector bundles over a Riemann surface of any genus. Next we find the first correction term for the quantum product of this moduli space and hence get the two leading terms of the relations satisfied by the natural generators of its quantum cohomology. Finally, we use this information to get a full description of the quantum cohomology of the moduli space when the genus of the Riemann surface is 3.

Source: http://arxiv.org/abs/alg-geom/9711013v1

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Sep 22, 2013
09/13

by
Tsafrir S. Kolatt; Matthias Bartelmann

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We propose a method to remove the mass sheet degeneracy that arises when the mass of galaxy clusters is inferred from gravitational shear. The method utilizes high-redshift standard candles that undergo weak lensing. Natural candidates for such standard candles are type Ia supernovae (SN Ia). When corrected with the light-curve shape (LCS), the peak magnitude of SN Ia provides a standard candle with an uncertainty in apparent magnitude of $\Delta m\simeq 0.1-0.2$. Gravitational magnification of...

Source: http://arxiv.org/abs/astro-ph/9708120v2

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Sep 21, 2013
09/13

by
Evalyn I. Gates; Geza Gyuk; Gilbert P. Holder; Michael S. Turner

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A simple interpretation of the more than dozen microlensing events seen in the direction of the LMC is a halo population of MACHOs which accounts for about half of the mass of the Galaxy. Such an interpretation is not without its problems, and we show that current microlensing data can, with some advantage, be explained by dark components of the disk and spheroid, whose total mass is only about 10% of the mass of the Galaxy.

Source: http://arxiv.org/abs/astro-ph/9711110v1

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Sep 18, 2013
09/13

by
Vasilios Zarikas

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We present the analysis of the phase transition for the two Higgs electroweak model. We have found that for a wide range of parameters the universe first tunnels to a new intermediate phase. This feature not only is very important by itself, but also provides the essential requirements for producing baryon asymmetry with only small explicit CP-violating terms in the two Higgs tree Lagrangian.

Source: http://arxiv.org/abs/hep-ph/9509338v2

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Sep 21, 2013
09/13

by
Helmut Satz

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1. Introduction 2. Charmomium Dissociation and Colour Deconfinement 3. J/Psi Production in Nuclear Collisions 4. Anomalous J/Psi Suppression 5. Outlook and Summary

Source: http://arxiv.org/abs/hep-ph/9711289v1